mmc: sdhci_am654: fix start loop index for TAP value parsing

ti,otap-del-sel-legacy/ti,itap-del-sel-legacy passed from DT
are currently ignored for all SD/MMC and eMMC modes. Fix this
by making start loop index to MMC_TIMING_LEGACY.

Fixes: 8ee5fc0e ("mmc: sdhci_am654: Update OTAPDLY writes")
Signed-off-by: Nitin Yadav <n-yadav@ti.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20231026061458.1116276-1-n-yadav@ti.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>